Nautical publications often have useful information on the locations of suitable anchorages.
Local knowledge is valuable but you should always refer to your charts when considering your anchoring options.
Good Bottom Structure - Try to pick bottom structure that best suits your anchor gear. Clay or mud bottoms are often the best choice. Avoid rocky areas that will hang up your anchor. You can confirm the type of bottom by using the appropriate chart of the area.
Shelter from Weather - Pick an area that is sheltered from the wind and strong currents. If possible you should select an anchorage that is protected from the wind on all sides, regardless of wind shifts. Another good option would be a cove offering protection from at least the existing wind condition.
Ample Water Depth - Choose a location that provides adequate water depths through all stages of the tide. An area that is too deep will allow the anchor to drag and an area too shallow poses the risk of going aground. It important to also be aware of any strong or reversing currents that may occur during high or low tide.
Nearby Navigational Hazards - Avoid anchoring near known navigational hazards. If an anchor drags, your vessel will be that much closer to danger.
Location to Adjacent Vessels - If possible, try to anchor away from other vessels. This will reduce potential incidents arising from an anchor dragging or accessing the anchorage.
Proximity to Other Traffic - Anchor outside and away from traffic lanes and vessel movement areas. The risk of collision will greatly be reduced.
Available Navigational Aids - Choose an anchorage that has several navigational aids available to it. These could be prominent landmarks, lighted navigation buoys or lights. These aids can be used to ensure that your anchor is holding properly.
Room to Swing - Pick an anchoring site that allows sufficient room for your boat to swing on its rode. Many boaters calculate a drag circle based on the length of their vessel and rode deployed. Using this information, a position fix can be taken periodically or an alarm set on electronic navigation equipment to warn of a dragging anchor.
Having selected a suitable spot, you should run in slowly, always approach the anchorage by heading into the wind or current whichever is stronger, preferably on some range ashore selected from marks identified on the chart, or GPS data to aid in locating the chosen spot. Use of two ranges will give the most precise positioning. Later, these aids will be helpful in determining whether the anchor is holding or dragging.